Ink jet printing has been currently identified as one of the most successful candidates for the technology of choice in the digitally controlled, electronic printing market. Two prominent forms of this technology are drop-on-demand (DOD) and continuous ink jet (CIJ). CIJ technology was identified as early as 1929, in U.S. Pat. No. 1,941,001 issued to Hansell. In the 1960s, CIJ printing mechanisms were developed that made use of acoustically driven printheads that created ink droplets of uniform size that would be appropriately deflected by electrostatics.
There have been numerous advances in the implementation of CIJ printers. For example, CMOS/MEMS integrated printheads with resistive heating elements can be used to break up a fluid column into drops and to steer (or deflect) the drops along desired trajectories, see, for example, U.S. Pat. Nos. 6,079,821; 6,450,619; 6,863,385; 6,213,595; 6,517,197; and 6,554,410.
Heat can be applied to the fluid column (or jet) via an electrical potential supplied to the printhead heaters. Frequent application of heat pulses creates small drops, whereas less frequent application of heat pulses creates larger drops. The use of heat to break up the drops allows control of drop size at each nozzle. The heat pulses can be small in amplitude and yet still accurately control drop break-off. Heat pulses can be applied symmetrically, for example when the heater is in the shape of a single ring surrounding a nozzle, or asymmetrically, for example when multiple heaters surround a nozzle only one of which is activated.
Heat pulses of larger amplitudes having larger energy content, when applied asymmetrically, cause drop steering (deflection) as well as drop break-off. In such cases, it is usually desirable for the amount of deflection to be as large as possible so that the drops not to be printed can be reliably directed to a catcher or gutter. However, the amount of deflection can be limited because heat pulses of larger amplitudes may cause the fluid to boil or to decompose thermally.
One way of increasing deflection includes adding constituents to the fluids to increase the temperature at which boiling or decomposition occurs. However, fluids so formulated may not be optimal for other functionalities, such as providing color gamete printed images. Another way of increasing deflection, disclosed in U.S. Pat. No. 6,830,320, includes reducing the operating temperature of the fluids and printhead. However the hardware required for such operation increases system complexity and cost.
As such, a need exists to provide increased or larger amounts of fluid jet deflection when compared to conventional deflection techniques for a variety of fluids under a variety of operating conditions without unnecessarily heating the fluids or increasing the likelihood of the fluids to decompose.